The present invention relates generally to cable tie fasteners for securing elongate objects in a bundle and more particularly to an improved locking head for a cable tie fastener.
A wide variety of cable ties are well known and in use for the securing and bundling of wires and cables in a variety of applications. Prior cable ties have utilized straps integrally formed with a locking head as well as separate straps that engage with a locking mechanism of the non-integral locking head. Prior cable ties have also utilized various forms of an integrally formed locking pawl or a metal locking clip to act as the locking mechanism. In certain applications such as installing communication wiring on outdoor poles, the cable ties need to be able to withstand the external environmental elements. Cable ties used in these environments are preferably made of a material which can provide excellent weatherability, high UV and corrosion resistance, have low moisture absorption and have flexibility at low temperatures. Polyoxymethylene (POM) polymers commonly known as acetals possess the desired characteristics noted above. Certain differences in the properties of the acetal material verses the commonly used nylon material for cable ties leads to a number of changes in the manufacture of bundling straps using the acetal materials. Specifically, the acetal materials do not flow easily in an injection molding process where an integrally formed strap also needs to be filled. Thus, cable tie fasteners made from acetal materials generally utilize a locking head and a separate bundling strap.
For all types of cable ties it is generally a goal to provide a cable tie that has a relatively high loop tensile strength but has a low strap insertion force. It is also a factor in designing cable ties to consider ease of manufacturing. Many of the designs which provide satisfactory ratios of loop tensile strength to strap insertion force have manufacturing difficulties which add to the costs. Therefore, improvement in the art is desired.
It is therefore an object of the present invention to provide an improved cable tie.
It is a further object of the present invention to provide an improved locking head for a cable tie.
It is still further an object of the present invention to provide an improved cable tie made of acetal resins or any similar propertied material.
In one embodiment, the invention is a cable tie for bundling together a plurality of elongated objects. The cable tie includes an elongated flexible strap having opposing ends, a locking head defining a pair of strap passageways, each of the passageways having an inlet end and an outlet end, and a pair of locking devices. Each of the pair of locking devices is mounted to the locking head and at least partially within one of the passageways. The locking devices are configured and oriented relative to the respective passageways so as to permit the ends of the strap to be inserted into the inlet ends of the passageways, and threaded through the passageways such that the ends emerge from the outlet ends of the passageways. The locking devices are unidirectional so as to prevent the strap ends from being pulled back through the respective passageways in a direction moving from the outlet ends back toward the inlet ends.